File IO

I am new on this ARM tool, What I trying to do is verify some simple ARM algorithm. What I need to do at this time is open a file on my local window machine, so I can read some array in then process it. So I start to use this uVision tool, start from simulator and example code. One problem I have now is, only the hello project works for me, once I added some file open things, such as fopen(), I got problem, for example, the fopen returned the "0x0" back. if I uncheck the Micolib, could not start to main().

I read this thread, http://www.keil.com/support/docs/3051.htm, there is different approach to save data, is there a way we can save the data directly into a file by using fwrite() under uVision?

Thanks a lot.
Huafeng